It's only available once a week, on Tuesday from 11:30 a.m. "until the meat runs out," but maybe that's one of the reasons we find ourselves dreaming of this burger on other days. And we're not alone: On that one day, the line at this popular sausage shack runs out the door, and nearly everybody orders the burger, often taking it next door to the Toronado pub, where you can wash it down with a beer. Rosamunde's is a classic concoction -- juicy patty, lettuce, tomato, mustard, ketchup, pickles, grilled onions, and cheese on a puffy bakery bun. This is a burger to cross the city for, a burger worth marking your calendar for. ("Why do you only serve them once a week?" a supplicant asks. "Because they're a pain in the ass!" is the cheerful reply.)